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Abstract:

Arrangement of joint packing between the pump-injector (injector) body (1)
and nozzle body (2) for internal combustion engines, primarily diesels,
wherein in order to increase the specific pressures between the faces of
joined precision surfaces of pump-injector (injector) body (1) and nozzle
body (2) (and also when there is an insert (3) installed between said
faces) pressed together by a nut (9), said surfaces have a reduced
contact area achieved by bounding these surfaces by a contour line (17)
surrounding the channels reaching out to said joints. This allows for
reliable sealing (joint packing) between pump-injector (injector) body
(1), nozzle body (2), and the face of the insert (3) at high injection
pressures (2500 Bar and higher).

Claims:

1. Arrangement of joint packing between the pump-injector (injector) body
and nozzle body for internal combustion engines primarily diesels,
comprising a body of the pump-injector (injector) and a nozzle body
(between which an insert can be installed), having flat precision faces
directly contacting each other, said faces having ends of communicating
high-pressure channels in the pump-injector body, insert and nozzle body
reaching out to their surfaces, said parts being centered one in relation
to another by pins whose bores also reach out to said faces, the faces
being pressed together by a tightening nut, the proposed arrangement
being distinguished by the fact that said faces of the pump-injector
body, insert and nozzle body contact each other along a surface bounded
by a contour line surrounding said channels and bores in such a way that
the area of contacting surfaces along which said faces are sealed is
smaller than the area corresponding to the total area of the face of the
nozzle unit body bounded by the maximum outer diameter of the nozzle
body.

2. Arrangement of joint packing according to claim 1, wherein said contour
line bounding the surface along which the pump-injector (injector) body,
insert and nozzle body contact each other, can be a single closed
continuous line or can consist of separate closed sections, the distance
between the points of said contour line and internal surface of said
channels, and pin bores in said bodies and insert being smaller than the
distance between internal surface of the ends of the channels in nozzle
body and the outer contour of the nozzle body.

Description:

TECHNICAL FIELD

[0001]The invention relates to the field of fuel supply systems for
internal combustion engines, specifically to diesels and, more
specifically, to their hydraulically driven pump-injectors and to
conventional pump-injectors.

BACKGROUND ART

[0002]In order to achieve greater fuel efficiency and lower exhaust
emission, the injection pressure in modern diesels, especially in
high-power diesels, should be increased to about 2000-2500 Bar and more.
This imposes stricter requirements for the reliability of the joint
packing between the pump-injector (or injector, hereinafter
"pump-injector") body and the body of the nozzle which in conventional
fuel systems is connected to the pump-injector body by a tightening nut.
To ensure the required tightness of the joint packing, the specific
pressures between the adjoining surfaces of said bodies should be 50-70%
higher than the actual injection pressures. To achieve this, the force
required to keep these bodies together is usually created by a tightening
nut, which leads to the increased tension in the nut itself; this may
affect the nut strength, lead to increased deformation of the nozzle body
and reduce the pump-injector reliability.

DISCLOSURE OF INVENTION

[0003]In the proposed arrangement of the joint packing between the
pump-injector body and nozzle body, the increase of the specific
pressures in the joint required at high injection pressures is achieved
not by increasing the force of keeping said bodies together by a
tightening nut, but by reducing the contact area of the face surfaces of
the pump-injector and nozzle bodies.

[0004]In accordance with the invention, the design environment for the
proposed invention contains pump-injector and of nozzle bodies that have
flat precision sealing faces contacting each other; the ends of
communicating high pressure channels located in said bodies, and bores
for the pins centering the bodies reach out to the surface of said faces.
In accordance with the invention, these bodies contact each other along
the surface bounded by a contour line so that the area of contacting
surfaces that seal said faces is smaller than the area corresponding to
the total area of the face of the nozzle body determined by the outer
diameter of the nozzle body. In accordance with the invention, the
contour line bounding the contacting area of the faces of the
pump-injector and nozzle bodies can be a single closed line, or consist
of individual closed sections. The distance between points on said
contour line and the internal surface of said channels and bores made for
the centering pins should be equal or greater than the distance between
the internal surface of the ends of high-pressure channels in nozzle body
and the outer contour of the nozzle body face. The arrangement of joint
packing between the pump-injector and nozzle bodies described above
allows for reducing the area of the contacting surfaces of the joint by a
factor of 1.5-2 and thus increasing the specific pressure in the joint
without exceeding the allowable tightening force of the nut, and
providing the conditions for the required level of sealing and reliable
functioning of the joint at high injection pressures.

SUMMARY OF THE INVENTION

[0005]FIG. 1 shows a functional diagram of joint packing in accordance
with the invention illustrated by a hydraulically driven pump-injector,
where (a), (b) and (c) illustrate possible contours of the contact
surfaces of the faces of the pump-injector and nozzle bodies.

[0006]In FIG. 1: 1--pump-injector body; 2--nozzle body; 3--insert between
the pump-injector and nozzle bodies; 4--cylindrical cavity in
pump-injector body 1; 5--channel in the pump-injector body connecting
cavity 4 with the drain tank; 6--plunger; 7--under-plunger cavity;
8--channel in the pump-injector body, through which the under-plunger
cavity is filled; 9--tightening nut; 10--the return spring of the nozzle
unit needle; 11--spring support; 12--nozzle unit needle; 13--channels in
pump-injector body 1 and insert 3, through which the fuel from
under-plunger cavity is supplied to the nozzle body; 14--channel in
nozzle body through which the fuel is supplied from channel 13 into
cavity 15 of the nozzle body; 15--cavity in nozzle body; 16--pins
centering the bodies of the pump-injector and nozzle with insert 3;
17--contour lines bounding the sealing contacting surfaces of joints A-A
and B-B. Below the description of the lower part of hydraulically driven
pump-injector with the arrangement of joint packing in accordance with
the invention is given.

[0007]In pump-injector body 1 in the area adjacent to insert 3,
cylindrical cavity 4 is formed which communicates with the drain tank
through channel 5, plunger 6 being also located and moving in said body.
Under-plunger cavity 7 is filled with fuel through channel 8.
Pump-injector body 1 and nozzle body 2 are pressed to insert 3 by nut 9.
In said cavity 4, return spring 10 is disposed which transfers the force
through support 11 to nozzle needle 12. The lower face of insert 3 limits
the travel of the needle which is pressed upon said face during its
travel upward. Under-plunger cavity 7 is connected via high-pressure
channels 13 in body 1 of the pump-injector and in insert 3, and also
through channel 14 in nozzle body 2 with internal cavity 15 of the nozzle
unit. The bodies of the pump-injector and of the nozzle and the insert
are centered with respect to each other by pins 16. Ends of channels 13
and 14, and bores of pins 16 out to the sealing surfaces of joints A-A
and B-B, and the purpose of the joint packing is prevention of fuel leaks
through abovementioned channels and bores. Contour lines 17 bounding the
contacting surfaces of the faces shown in FIG. 1 (a, b, c) are possible
examples of the form of the contacting sealing surfaces.

BEST MODE FOR CARRYING OUT THE INVENTION

[0008]As mentioned above, the contour lines bounding the contacting
surfaces of the joint can be made continuous (FIGS. 1a and 1b), or
discontinuous and discrete (dashed) (FIG. 1c). The form of the contour
line should be selected based on the actual design of the bodies of the
pump-injector and nozzle units. It should be provided that the minimum
distance (bridge "m", see FIG. 1) between the inner surface of the
channels and the bores for pins coming out to the sealing joints, and the
contour lines are equal or greater than the distance "n" (bridge "n", see
FIG. 1) between said bores and outer contour of the cylindrical nozzle
body. Such limiting of the "m" distance ensures a reliable joint sealing
at high pressures (2500 Bar and higher) which is not less reliable than
conventional systems where the injection pressures do not exceed
1000-1200 Bar.

[0009]Providing a reduced contact area of the contacting sealing surfaces
is easiest on the pump-injector body and on the insert. In this case, one
can use conventional designs of nozzle units and their bodies which are
manufactured using a special technology.

[0010]It will be evident to those skilled in the art that the invention is
not limited to the details of the foregoing illustrated embodiments and
that the present invention may be embodied in other specific forms
without departing from the spirit or essential attributes thereof. The
present embodiments are therefore to be considered in all respect as
illustrative and not restrictive, the scope of the invention being
indicated by the appended claims rather than by the foregoing
description, and all changes which come within the meaning and range of
equivalency of the claims are therefore intended to be embraced therein.

INDUSTRIAL APPLICABILITY

[0011]Arrangement of joint packing between the pump-injector (injector)
body and the nozzle body in accordance with the invention can be used for
sealing the joints both in conventional injectors and in pump-injectors.
It is especially advisable to use the joint packing in accordance with
the invention in hydraulically driven pump-injectors. This is because in
hydraulically driven pump-injectors, high injection pressures are
normally used (2000 Bar, which may soon increase to 2500 Bar and higher)
requiring a reliable sealing of said joint without increasing the
tightening force of the tightening nut. The problem of sealing the joints
is important because we are dealing with larger injectors which are
typical of large diesels, such as diesels used for off-road vehicles,
locomotives, and marine applications and have larger face areas and,
consequently, larger areas of contacting surfaces. Therefore the joint
packing in accordance with the invention should be preferably used in
diesels of the above mentioned applications.